feat: align Azure/GCP SDKs with namespace vision (API-1988)

[Nelson-PROIA]

Summary

Migrate Azure/GCP from standalone flat packages (mistralai_azure, mistralai_gcp) into PEP 420 namespace sub-packages within the main mistralai tree, aligned with the existing mistralai.client pattern.

# Before
from mistralai_azure import MistralAzure
from mistralai_gcp import MistralGoogleCloud

# After
from mistralai.azure.client import MistralAzure
from mistralai.gcp.client import MistralGCP

What changed

• Directory renames: packages/mistralai_azure/ → packages/azure/, packages/mistralai_gcp/ → packages/gcp/
• gen.yaml: set moduleName to mistralai.azure.client / mistralai.gcp.client, bumped version to 2.0.0a4, enabled v2 config flags (see docs/gen-yaml-diff.md for full comparison)
• Regenerated both SDKs under the new namespace structure via speakeasy run
• Hatch build config: updated source mappings to merge three mistralai/ trees into one wheel — the generated code now lives at packages/azure/src/mistralai/azure/client/ and packages/gcp/src/mistralai/gcp/client/
• dev-mode-dirs: required for editable installs (uv sync) — the Azure/GCP code lives in separate source directories (packages/azure/src/, packages/gcp/src/), and hatch needs to be told to put all three dirs on sys.path so that import mistralai.azure.client works at runtime
• Cross-package consistency fixes: pydantic >=2.11.2, mypy ==1.15.0, package names with hyphens (mistralai-azure, mistralai-gcp), MistralGCPError class naming, .genignore alignment
• Examples: updated imports and constructor args, removed duplicate example files (az_chat_no_streaming.py, gcp_async_chat_no_streaming.py)
• Lint script: updated scripts/lint_custom_code.sh paths for new directory structure
• Parity tests: 157 Azure + 188 GCP parametrized introspection tests covering constructor, context manager, all chat/ocr/fim params, sync/async parity
• Integration tests: credential-gated tests for Azure chat and GCP chat + FIM (sync/async/streaming/tools/JSON)
• run_examples.sh: excluded fine-tuning job examples — they fail due to open-mistral-7b no longer being available for fine-tuning (pre-existing issue on main)

Test plan

• 347 tests pass, 42 skipped (credential-gated integration tests)
• All linters pass (mypy, pyright, ruff)
• PEP 420 namespace integrity verified
• Wheel builds with all three SDK trees merged
• Editable installs resolve all imports correctly
• Manual smoke test with Azure credentials
• Manual smoke test with GCP credentials

[louis-sanna-dev]

@Nelson-PROIA I think it looks good, not an expert in python packaging to be fair.

Let's also check how to QA with actual Azure/GCP endpoints.

Two nitpicks proposed by Claude:

• README import path inconsistency
  • README shows: from mistralai.azure import MistralAzure
  • Examples use: from mistralai.azure.client import MistralAzure[4:38 PM]  
• Duplicate example files
  • examples/azure/az_chat_no_streaming.py and examples/azure/chat_no_streaming.py are identical
  • examples/gcp/async_chat_no_streaming.py and examples/gcp/gcp_async_chat_no_streaming.py are identical